diff --git a/lib/tests/filesystem.sh b/lib/tests/filesystem.sh
new file mode 100755
index 000000000000..ab1504abb490
--- /dev/null
+++ b/lib/tests/filesystem.sh
@@ -0,0 +1,88 @@
+#!/usr/bin/env bash
+
+# Tests lib/filesystem.nix
+# Run:
+# [nixpkgs]$ lib/tests/filesystem.sh
+# or:
+# [nixpkgs]$ nix-build lib/tests/release.nix
+
+set -euo pipefail
+shopt -s inherit_errexit
+
+# Use
+#     || die
+die() {
+  echo >&2 "test case failed: " "$@"
+  exit 1
+}
+
+if test -n "${TEST_LIB:-}"; then
+  NIX_PATH=nixpkgs="$(dirname "$TEST_LIB")"
+else
+  NIX_PATH=nixpkgs="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.."; pwd)"
+fi
+export NIX_PATH
+
+work="$(mktemp -d)"
+clean_up() {
+  rm -rf "$work"
+}
+trap clean_up EXIT
+cd "$work"
+
+mkdir directory
+touch regular
+ln -s target symlink
+mkfifo fifo
+
+checkPathType() {
+    local path=$1
+    local expectedPathType=$2
+    local actualPathType=$(nix-instantiate --eval --strict --json 2>&1 \
+        -E '{ path }: let lib = import <nixpkgs/lib>; in lib.filesystem.pathType path' \
+        --argstr path "$path")
+    if [[ "$actualPathType" != "$expectedPathType" ]]; then
+        die "lib.filesystem.pathType \"$path\" == $actualPathType, but $expectedPathType was expected"
+    fi
+}
+
+checkPathType "$PWD/directory" '"directory"'
+checkPathType "$PWD/regular" '"regular"'
+checkPathType "$PWD/symlink" '"symlink"'
+checkPathType "$PWD/fifo" '"unknown"'
+
+checkPathIsDirectory() {
+    local path=$1
+    local expectedIsDirectory=$2
+    local actualIsDirectory=$(nix-instantiate --eval --strict --json 2>&1 \
+        -E '{ path }: let lib = import <nixpkgs/lib>; in lib.filesystem.pathIsDirectory path' \
+        --argstr path "$path")
+    if [[ "$actualIsDirectory" != "$expectedIsDirectory" ]]; then
+        die "lib.filesystem.pathIsDirectory \"$path\" == $actualIsDirectory, but $expectedIsDirectory was expected"
+    fi
+}
+
+checkPathIsDirectory "$PWD/directory" "true"
+checkPathIsDirectory "$PWD/regular" "false"
+checkPathIsDirectory "$PWD/symlink" "false"
+checkPathIsDirectory "$PWD/fifo" "false"
+checkPathIsDirectory "$PWD/non-existent" "false"
+
+checkPathIsRegularFile() {
+    local path=$1
+    local expectedIsRegularFile=$2
+    local actualIsRegularFile=$(nix-instantiate --eval --strict --json 2>&1 \
+        -E '{ path }: let lib = import <nixpkgs/lib>; in lib.filesystem.pathIsRegularFile path' \
+        --argstr path "$path")
+    if [[ "$actualIsRegularFile" != "$expectedIsRegularFile" ]]; then
+        die "lib.filesystem.pathIsRegularFile \"$path\" == $actualIsRegularFile, but $expectedIsRegularFile was expected"
+    fi
+}
+
+checkPathIsRegularFile "$PWD/directory" "false"
+checkPathIsRegularFile "$PWD/regular" "true"
+checkPathIsRegularFile "$PWD/symlink" "false"
+checkPathIsRegularFile "$PWD/fifo" "false"
+checkPathIsRegularFile "$PWD/non-existent" "false"
+
+echo >&2 tests ok
diff --git a/lib/tests/release.nix b/lib/tests/release.nix
index dbf6683d49a8..f5c6e81030ca 100644
--- a/lib/tests/release.nix
+++ b/lib/tests/release.nix
@@ -44,6 +44,9 @@ pkgs.runCommand "nixpkgs-lib-tests" {
     echo "Running lib/tests/modules.sh"
     bash lib/tests/modules.sh
 
+    echo "Running lib/tests/filesystem.sh"
+    TEST_LIB=$PWD/lib bash lib/tests/filesystem.sh
+
     echo "Running lib/tests/sources.sh"
     TEST_LIB=$PWD/lib bash lib/tests/sources.sh